The invention relates to a linear guide device comprising a guide base having a longitudinal axis, a runner assembly guided relative to said guide base in the direction of said longitudinal axis, a linear drive means for driving said runner assembly along said longitudinal axis, said linear drive means including a drive spindle supported at at least one of its ends axially fixedly, but rotatably, relative to said guide base, and including a nut being in threaded engagement with said drive spindle, said nut being connected with said runner assembly for movement in the direction of said longitudinal axis and being lockable or brakable against rotation with said drive spindle, and at least one spindle support unit at each of axially both sides of said runner assembly, each said spindle support unit being guided relative to said runner assembly on said guide base in the direction of said longitudinal axis, said spindle support units being displaceable along said longitudinal axis within a respective longitudinal distance between said runner assembly and a respective spindle end in dependence on movements of said runner assembly.
In such a linear guide device the maximum movement speed of the runner assembly relative to the guide base depends on the socalled critical speed of the drive spindle. When reaching the critical speed the drive spindle is set to self-induced vibration whose amplitude makes a precise positioning of the runner assembly impossible. Substantial factors which determine the critical speed are the diameter of the spindle and its length. The smaller the diameter/length ratio of the drive spindle is, the lower is the critical speed and, accordingly, the maximum movement speed of the runner assembly. Since particularly in the case of great lengths of the drive spindle (e.g. several meters) the spindle diameter cannot be enlarged at will for reasons of dimensions or weight, additional spindle support units are arranged in the support-free longitudinal portions of the drive spindle between the runner assembly and the spindle ends. The spindle support units represent additional support locations for the drive spindle and shorten the length of the support-free spindle portions. The critical speed of the drive spindle and the maximum movement speed of the runner assembly are increased in this manner. Furthermore, the spindle support units prevent deformation especially in the case of long drive spindles. The spindle support units are movable in relationship to the runner assembly and displaceable dependent on a movement of the runner assembly along the longitudinal axis so that they shorten the maximum displacement path of the runner assembly along the longitudinal axis, which is predetermined by the spindle length, only by their respective overall length.